This invention relates to a device which automatically controls the elongation of an operating wire for a brake system in a two-wheeled motor vehicle, or the like. In such a vehicle, an operating wire is usually provided between a brake operating lever and a brake unit to transmit a force from the brake operating lever to the brake unit. The wear of a brake lining in the brake unit or the elongation of the operating wire per se results in an increased play stroke of the wire which requires gradual changes in the application and "feel" of the brake operation.